I was thinking about this thread last night, namely that the OP stated a number of times the question of why a certain highlight softness/glow/bleed happened on Type 55 and not PX. And I was thinking Type 55 had a tonal antiqueness, for lack of better words, sure, but it was not THAT old school.
So I then wondered, what was the Type 55 shot at and what was the plus-x shot at, b/c I'd say PX is about two stops faster than Type 55. Then I wondered if and where that exposure compensation was made between the two. If it was made via F stop, then that right there would explain the differences in what was seen on each. Type 55 wide open, vs PX two clicks down, optic characteristics will have way more say than emulsion characteristics. Now if the exposure was compensated for via shutter speed than this lengthy post was in vain.
Anyway, just crossed my mind, as I didn't believe it'd been mentioned, unless I skimmed over it.